The Gut Brain Connection
Leaky gut? Leaky brain?
If you have gut problems in addition to cognitive difficulties, your functional medicine provider might start with treating your gut. Why is this?
“A leaky gut causes a leaky brain” is a common statement heard among functional medicine providers, but it’s not commonly discussed in the world of conventional medicine. So, how connected are the brain and the gut?
We can start by understanding that there is indeed bidirectional communication between the gut microbiome and the brain. This communication happens via the vagus nerve, the body’s superhighway that sends electrical signals both to the brain and to other organs in our body -- including the gut.
We also know that a disordered gut is associated with many chronic diseases, such as rheumatoid arthritis, types 2 diabetes, cardiovascular disease, hypertension, and inflammatory bowel disease (Vijay & Valdes, 2022; Wang et al., 2021).
Doctors widely acknowledge these connections between the gut and the brain. For example, doctors may even prescribe medications like antidepressants, which act on neurotransmitters found in the brain (and the gut), for many chronic gut concerns. But does this gut-brain relationship work in the other direction? Can the health of the gut affect the health of the brain? Could gut issues be the root cause of common mental symptoms such a brain fog, forgetfulness, or trouble completing tasks?
The answer is “yes” – this gut-brain relationship works both ways. There is growing evidence that dysbiosis, or the imbalance of “good” and “bad” bacteria in our guts, leads to inflammation that affects our brains and may even cause Alzheimer’s (Grabrucker et al., 2023). Our brain’s “clean-up crew,” known as microglia, cannot effectively resolve the inflammation caused by this imbalance, especially for those genetically susceptible (Bellenguez et al., 2022). Furthermore, gut dysbiosis produces fewer of those substances (such as butyrate) that typically help us resolve inflammation throughout our bodies (Liu et al., 2018).
We also know that a condition known as “leaky gut,” in which the mucosal barrier in the intestines becomes disrupted, causes substantial inflammation. I like to think of the gut as a filter, which must allow for the diffusion of nutrients, but which should not allow larger molecules to pass. In a “leaky gut,” larger-than-normal proteins can escape our intestines and enter our bloodstream, where they are difficult for our bodies to manage. Our natural immune response to these unusual proteins can lead to auto-immune illnesses and allergies. This may be why certain people develop novel sensitivities to foods that previously didn’t bother them: particles of those foods are escaping through the broken membranes in their “leaky gut” and triggering new immune reactions.
Additionally, “bad” bacteria, such as e. Coli, can escape into the bloodstream through these broken mucosal walls. Although our immune system typically manages this, it causes further inflammation and leads to an even leakier gut, due to physical damage caused by lipopolysaccharides (LPS) in the bacteria’s cells.
Let’s review:
There is bidirectional communication between the gut and the brain.
Many chronic diseases are associated with gut dysbiosis (an imbalance of good and bad bacteria).
Gut dysbiosis leads to inflammation and produces damaging byproducts that can cross the blood-brain barrier.
Genetically susceptible individuals have a reduced ability to “clean up” this inflammation, which causes damage to the neurons.
A leaky gut allows proteins and gram negative bacteria into the bloodstream, which causes inflammation and produces substances that further damage the blood-brain barrier.
With all this information available, it makes sense to “start with the gut” when healing cognitive problems!
The good news: we now have testing that can identify dysbiosis, markers for leaky gut, and LPS in the intestines. Find out more about gut healing and why it might be right for you: Send up a message in messenger or contact us at cheryl@vitalmindfunction.com.
Bellenguez, C., Küçükali, F., Jansen, I. E., Kleineidam, L., Moreno-Grau, S., Amin, N., Naj, A. C., Campos-Martin, R., Grenier-Boley, B., Andrade, V., Holmans, P. A., Boland, A., Damotte, V., van der Lee, S. J., Costa, M. R., Kuulasmaa, T., Yang, Q., de Rojas, I., Bis, J. C., … Lambert, J.-C. (2022). New insights into the genetic etiology of Alzheimer’s disease and related dementias. Nature Genetics, 54(4), 412–436. https://doi.org/10.1038/s41588-022-01024-z
Grabrucker, S., Marizzoni, M., Silajdžić, E., Lopizzo, N., Mombelli, E., Nicolas, S., Dohm-Hansen, S., Scassellati, C., Moretti, D. V., Rosa, M., Hoffmann, K., Cryan, J. F., O’Leary, O. F., English, J. A., Lavelle, A., O’Neill, C., Thuret, S., Cattaneo, A., & Nolan, Y. M. (2023). Microbiota from Alzheimer’s patients induce deficits in cognition and hippocampal neurogenesis. Brain, 146(12), 4916–4934. https://doi.org/10.1093/brain/awad303
Liu, H., Wang, J., He, T., Becker, S., Zhang, G., Li, D., & Ma, X. (2018). Butyrate: A Double-Edged Sword for Health? Advances in Nutrition, 9(1), 21–29. https://doi.org/10.1093/advances/nmx009
Peng, X., Luo, Z., He, S., Zhang, L., & Li, Y. (2021). Blood-Brain Barrier Disruption by Lipopolysaccharide and Sepsis-Associated Encephalopathy. Frontiers in Cellular and Infection Microbiology, 11. https://doi.org/10.3389/fcimb.2021.768108
Vijay, A., & Valdes, A. M. (2022). Role of the gut microbiome in chronic diseases: A narrative review. European Journal of Clinical Nutrition, 76(4), 489–501. https://doi.org/10.1038/s41430-021-00991-6
Wang, X., Chen, Z., Geng, B., & Cai, J. (2021). The Bidirectional Signal Communication of Microbiota-Gut-Brain Axis in Hypertension. International Journal of Hypertension, 2021, 8174789. https://doi.org/10.1155/2021/8174789
